Journal of Experimental Criminology

, Volume 9, Issue 2, pp 213–244 | Cite as

A randomized test of initial and residual deterrence from directed patrols and use of license plate readers at crime hot spots

  • Christopher S. Koper
  • Bruce G. Taylor
  • Daniel J. Woods



To test the effects of short-term police patrol operations using license plate readers (LPRs) on crime and disorder at crime hot spots in Mesa, Arizona.


The study employed a randomized experimental design. For 15 successive 2-week periods, a four-officer squad conducted short daily operations to detect stolen and other vehicles of interest at randomly selected hot spot road segments at varying times of day. Based on random assignment, the unit operated with LPRs on some routes and conducted extensive manual checks of license plates on others. Using random effects panel models, we examined the impact of these operations on violent, property, drug, disorder, and auto theft offenses as measured by calls for service.


Compared to control conditions with standard patrol strategies, the LPR locations had reductions in calls for drug offenses that lasted for at least several weeks beyond the intervention, while the non-LPR, manual check locations exhibited briefer reductions in calls regarding person offenses and auto theft. There were also indications of crime displacement associated with some offenses, particularly drug offenses.


The findings suggest that use of LPRs can reduce certain types of offenses at hot spots and that rotation of short-term LPR operations across hot spots may be an effective way for police agencies to employ small numbers of LPR devices. More generally, the results also provide some support for Sherman’s (1990) crackdown theory, which suggests that police can improve their effectiveness in preventing crime through frequent rotation of short-term crackdowns across targets, as it applies to hot spot policing.


Crackdowns Hot spots License plate readers Policing Randomized experiment Technology 



This project was supported by grant 2007-IJ-CX-0023 awarded by the National Institute of Justice (Office of Justice Programs, U.S. Department of Justice). The authors thank the Mesa, AZ Police Department (MPD) for its strong commitment to the project. We especially thank the auto theft unit officers, (Officers James Baxter, Joel Calkins, Stan Wilbur, and Brandon Hathcock), supervisory officer Cory Cover, Deputy Chief John Meza, and other MPD commanders. Also, the authors are very appreciative of Dr. Yongmei Lu for her work conducting geographic analyses. Finally, the authors thank David Weisburd and other anonymous peer reviewers for their helpful comments on an earlier version of this paper. The views expressed here are those of the authors and should not be attributed to the U.S. Department of Justice, the Mesa, AZ Police Department, the authors’ respective institutions, or any of the aforementioned individuals.


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Christopher S. Koper
    • 1
  • Bruce G. Taylor
    • 2
  • Daniel J. Woods
    • 3
  1. 1.Department of Criminology, Law and SocietyGeorge Mason UniversityFairfaxUSA
  2. 2.NORC at the University of ChicagoBethesdaUSA
  3. 3.Police Executive Research ForumWashingtonUSA

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